In a wall-mounted air conditioner, a temperature sensor used for detecting an indoor temperature is disposed close to an air inlet. In the prior art, the temperature sensor is disposed on a surface of an evaporator close to the air inlet. However, as being close to the evaporator, the temperature sensor tends to suffer a thermal radiation of the evaporator, thus causing an apparent difference between an obtained ambient temperature and an actual ambient temperature. In addition, a signal wire connected to the temperature sensor tends to contact and rub fins of the evaporator in the assembling process, which may cause the signal wire to be cut off by the fins, even disable the temperature sensor, and also provide a potential safety risk. In some other cases, the temperature sensor is disposed to a cover plate of an electric motor, which, however, will cause a narrow air inlet channel.